This invention relates to an exposure apparatus, and more particularly to a reduction projective type Excimer exposure apparatus which is capable of realizing super fine processing in photolithography processes for use in fabrication of semiconductor devices.
In the past, commercially available reduction projective type exposure apparatus (stepper) was of the structure in which super high pressure mercury lamp is used as light source for fine processing of semiconductor devices, in particular LSI, VLSI. However, since such conventional stepper uses g-line (436 nm), i-line (365 nm) of super high pressure mercury lamp, its resolution has some limitations; approximately 1.2 .mu.m for g-line and approximately 0.8 .mu.m for i-line.
To overcome such limitations, recently some developments have been moved forward. In such development, Excimer light source, e.g., XeCl (308 nm), KrF (249 nm), ArF (193 nm) whose wavelength is shorter than that of g-line, i-line.
However, since Excimer light source makes use of a high voltage pulse discharge, vibration occurs due to shock wave upon oscillation and it gives bad effects to alignment and exposure operation. Further, it is necessary to provide large space for installing the light source, which gives bad effects to manufacturing semiconductor devices wherein expensive super clean room is required.
As to the problem of vibration, we can get some extent of solution by mounting all elements such as a light source, lens system, wafer stage, mask holder on the same base with vibration protection structure, but in such case, installation space for the exposure apparatus becomes three times larger than that in conventional way.